The present invention relates to a printing apparatus, particularly, it relates to a printing apparatus having an expanded pitch mode and an underline mode.
In general, in the printing apparatus such as an electronic typewriter, a function for setting an auto underline mode wherein, just after printing characters and symbols, underlines are automatically printed under the characters and symbols, and a print pitch selecting function capable of selecting a print pitch between a pica pitch (10 characters/in.) and an elite pitch (12 characters/in.) are included.
Furthermore, the applicant of the present invention has proposed, in our previous application (Japanese Utility Model Pat. Application No. 75765/1987), a printing apparatus including a print pitch expanding function capable of printing at an expanded print pitch, for example, equal to doubled pitch of a selected print pitch. That is, in this printing apparatus, code data of the character or symbol and attribute data such as pitch data and underline data are stored in a line buffer in 2 bytes corresponding to the print position so that print pitches such as the "pica pitch" and "elite pitch" can be switched selectably, and an "expanded pitch" key for setting an expanded pitch mode corresponding to twice the selected print pitch is provided. When the expanded pitch mode is set, expanded pitch data are stored in the line buffer as the pitch data so as to print the character inputted successively at the expanded pitch.
In the printing apparatus, as shown in FIG. 10(a), when both the auto-underline mode and expanded pitch mode are set, data representing the underline are given respectively to the attribute data of entered characters "A", "B", and the characters "A" and "B" corresponding to the data inputted are printed and the underline is printed at an expanded space portion succeeding the printed characters.
According to the printing apparatus of the previous application, as shown in FIG. 10(a), though each underline is printed under respective printed characters "A" and "B" as well as at the expanded space portion after printing the respective characters, such a problem is encountered that the character string printed with the underline at an expanded pitch is not suitably underlined, and is unbalanced, since the last underline is printed protrudently on the right hand side of the end character of the character string printed at the expanded pitch.
In addition, since only the code data and attribute data of respective printed characters are stored in the line buffer, when the printed characters are erased as shown in FIG. 10(b), only the characters and their underlines are erased but the underline printed at the expanded space portion between the characters remains as it is.